Correlation of the Catalytic Activity of Pyridines and N-Pyridine Oxides with Their Basicity

N-Pyridine oxides much stronger catalyze formation of organophosphorus thiosemicarbazides than pyridines, even though these two groups of catalysts compare in basicity. Separate correlations were found for pyridines and N-pyridine oxides of the catalytic rate constants with the basicity constants in water and nitromethane, as well as with the abilities of the catalysts to H-bond formation. The high catalytic activity of N-pyridine oxides is associated with the manifestation of the α-effect in the reaction studied.